Analysis of some metabolic conditions promoting selective sensitivity of tumor cells to peroxidative stress.

Some metabolic parameters enhancing the sensitivity of tumor cells and their lipoprotein refractive granules (RG) to peroxidative stress were investigated during the growth cycle of ascite tumors in vivo. The majority of tumor cells only in the stationary growth phase had the increased sensitivity to peroxidative stress, tested by fluorescence intensivity of peroxidation products. The increase of this intensity correlates well with the decrease of tumor proliferation, the functional activity of mitochondria, the cellular level of ATP and extracellular pH. These metabolic conditions are favourable for increasing the neutral lipid accumulation in the stationary tumor cells, their RG and nuclei, as compared to exponentially growing cells. The sensitivity of tumor cells to peroxidation can be also enhanced with the help of exogenous polyunsaturated fatty acid (PUFA). Based on literature and our own data on Ehrlich ascites carcinoma (EAC), a working hypothesis is proposed to explain the enhanced selective sensitivity of tumor cells to PUFA peroxidation products (PP) suppressing the cell growth (especially in the stationary phase of EAC growth).